Packaging bags provided with a zipper tape with a cut tape are easy to open and close and have an excellent sealing performance, and are therefore widely employed as packaging bags for storing food items as well as for packaging a variety of other articles such as chemicals, clothing items, industrial components, and general goods.
A packaging bag provided with a zipper tape with a cut tape of such description is sealed by sealing the upper part of the zipper tape, and can be unsealed by tearing a bag body film of the packaging bag using the cut tape.
A known example of a packaging bag provided with a zipper tape with a cut tape of such description includes a packaging bag in which a strip-shaped sheet having a ridge, a strip-shaped sheet having a groove which engages with the ridge, and a cut tape are bonded to a bag body (see Patent Document 1). However, in the invention disclosed in Patent Document 1, because each of the two strip-shaped sheets and the cut tape are bonded to the bag body, a problem is presented in that when the seal is opened, when stretching or a similar deformation occurs when the bag body is torn by the cut tape, the ridge and the groove become misaligned, making it difficult to open and close the zipper tape. In addition, since there is a need to bond the members to the bag body at three locations, a problem is presented in an increased rate of defectives due to defective bonding.
Also known is a bag to which is bonded a zipper tape with a cut tape formed of a first base material integrally provided with a cut tape and a second base material provided with a member which engages with the member formed on the first base material (see Patent Document 2). In the invention disclosed in Patent Document 2, only the first base material is bonded to the bag body; therefore, it is possible to reduce the defectives rate due to defective bonding. However, in the zipper tape disclosed in Patent Document 2, the zipper tape is integrally provided to the first base material; therefore, a problem is presented in regard to increased difficulty when adjusting the force necessary to separate the cut tape. In addition, in the zipper tape disclosed in Patent Document 2, it is necessary to bond an end part of the second base material at a position displaced from the portion of the first base material at which the cut tape is formed. However, a problem is presented that in order to bond or fuse the end part of the second base material so as to not overlap with the cut tape portion of the first base material and to prevent the engaging parts provided to the first base material and the second base material from becoming misaligned, the bonding step becomes cumbersome.